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Show 1886.] MR. J. B. SUTTON ON ATAVISM. 553 pocularis, utriculus, or uterus masculinus. Usually it is nearly an inch long, and opens by a narrow slit in the middle of the caput gallinaginis. It is lined by mucous membrane continuous with that of the urethra, and covered by stratified epithelium. Some small tubular glands open on the free surface of the mucous membrane. This utriculus is of great interest morphologically, as it represents in the male a persistent portion of the confluent segment of the Mullerian ducts. Weber regarded it as corresponding with the uterus, but Leuckart showed that a part of it must be looked upon as representing the vagina. M y observations induce me to regard the prostate as a suppressed uterus, the fibro-muscular tissue representing the matricial walls, the follicles correspond to the utricular glands, and the utriculus is identical with the cervix uteri and that portion of the vagina immediately adjacent. The evidence in support of this view will now be put before the reader. In order to render every detail in clear light, we must refer briefly to the fundamental structures concerned in forming a functional uterus. In the Lizard, in common with the majority of the Sauropsida, the ova are conveyed to the exterior by two muscular tubes lined with raucous membrane, known as oviducts. The eggs, when they escape from the ovaries, are received by the dilated end of the oviduct, known as the infundibulum, and quickly passed onwards ; they receive at the commencement of the journey a coating of albumen. Pushed on by the contortions of the tube, they arrive at the third or uterine portion. Here they receive a coating of calcareous matter known as the shell, and are then ready for expulsion. In these oviducts, with their mucous membranes and glands, we have the fundamental condition of the ducts which in the human embryo conspire to form the uterus with its Fallopian tubes and vagina. In order to clearly describe the manner in which the Fallopian tubes, uterus, and vagina are formed from the Miillerian ducts of opposite sides, each duct may be conceived as made up of three parts :- The upper third becomes the Fallopian tube; the funnel-shaped and usually fimbriated extremity communicates with the peritoneal cavity. The middle portions of the ducts fuse together, and form the fundus, body, and neck of the uterus, whilst the lower thirds of the Miillerian ducts form a vagina. Such is the commonest arrangement. On comparing the parts of this compound organ with the Lizard's oviduct, it becomes evident that the infundibulum and albumen segment in the bird represent the Mammalian Fallopian tube, the second or uterine portion corresponding with the uterus and vagina of Eutheria. On tracing the homologies closer, we find that the portion ot the bird's oviduct concerned in secreting albumen corresponds with that portion of the Mullerian duct which forms the fundus and body of the uterus; and the utricular glands, which are concerned in |